What do we know from experiments with GMO mosquitoes released to fight disease?

Preliminary data from the first field trial in the United States is positive and suggests the goal of killing mosquitoes that can transmit viruses such as Chikungunya, Dengue, Zika and Yellow Fever can be achieved.

Preliminary data from the first outdoor experiment aimed at reducing the problem of mosquitoes that transmit dangerous diseases such as chikungunya, dengue fever, zika and yellow fever are positive. Biotech company Oxitec, which has developed insects and released nearly five million mosquitoes, said the news Aedes aegypti developed in the Florida Keys, a chain of tropical islands stretching near the southern tip of the US state of Florida, where scientists have almost completed monitoring the release sites.

Oxitec, based in Abingdon, UK, reported initial results from the study in a webinar on April 6, although full data has not yet been released. The experiment, launched last year, was used to test a method of suppressing these dangerous insects in real-world conditions, having already been tested in the field in Brazil, Panama, the Cayman Islands and Malaysia.

As already mentioned, wild mosquitoes A. aegypti They can carry viruses like chikungunya, dengue, zika, and yellow fever, so scientists have long sought ways to reduce these populations. In particular, Oxitec has developed males of A. aegypti Carrier of a deadly gene to female offspring with the ultimate goal of killing the wild population of potentially virus-carrying mosquitoes. In other words, once released into the environment, the modified males would have to mate with wild females and pass the deadly gene to the female offspring, who would have to die before they could reproduce. As more women die, the population decreases A. aegypti it should therefore decrease.

The experience in the US

To make sure the mosquitoes followed this pattern, the researchers placed boxes of Oxitec mosquito eggs on some private properties in the Florida Keys and surrounded them with traps that covered a radius of more than 400 meters. Some traps, the researchers explained, served as egg-laying sites, while others caught adult mosquitoes.

The artificial, non-biting males mated with the wild population, and the wild females laid their eggs in Oxitec traps, as well as other places like flower pots, trash can lids, and soda cans. In all, the researchers collected more than 22,000 eggs from the traps and brought them to their lab for hatching for observation.

Oxitec reported that all of the women who inherited the deadly gene died before reaching adulthood. ” The researchers were able to determine whether the gene was inherited because mosquitoes that carry it fluoresce under a certain light. – explains an article about Nature -. In addition, the team found that in the wild population, the killer gene persisted for two to three months, or about three generations, of mosquito offspring and then died out.“.

Outside the 400 meter radius of the release site, no mosquito carrying the deadly gene has been identified, even after several generations. Oxitec monitored release sites for ten weeks after discovering the last mosquito carrying the deadly gene. ” I like how they know by doing the experiment said Thomas Scott, a University of California entomologist who was involved with the research. They carry out the test in a systematic and thoughtful manner, even if they still have a lot of work ahead of them“.

This pilot study was not intended to determine the effectiveness with which the method can kill the wild population, so additional testing is needed to verify whether, thanks to this technique, it is possible to control wild populations that may be carrying the virus. Oxitec plans to collect this data through a study extension in the Florida Keys, but it must first be re-approved by state regulators. The company also plans to release artificial mosquitoes at a second study site in Visalia, California, where it is currently building a research and development facility.

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